package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.dto.ScrollResult;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Blog;
import com.hmdp.entity.Follow;
import com.hmdp.entity.User;
import com.hmdp.mapper.BlogMapper;
import com.hmdp.service.IBlogService;
import com.hmdp.service.IFollowService;
import com.hmdp.service.IUserService;
import com.hmdp.utils.SystemConstants;
import com.hmdp.utils.UserHolder;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ZSetOperations;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import static com.hmdp.utils.RedisConstants.BLOG_LIKED_KEY;
import static com.hmdp.utils.RedisConstants.FEED_KEY;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog> implements IBlogService {
    @Resource
    private IUserService userService;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private IFollowService followService;

    @Override
    public Result queryHotBlog(Integer current) {
        // 根据用户查询
        Page<Blog> page = query()
                .orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        // 获取当前页数据
        List<Blog> records = page.getRecords();
        // 查询用户
        records.forEach(blog -> {
            this.queryBlogUser(blog);
            this.isBlogLiked(blog);
        });
        return Result.ok(records);
    }

    @Override
    public Result queryBlogById(Long id) {
        //1.查询blog
        Blog blog = getById(id);
        if (blog == null) {
            return Result.fail("笔记不存在");
        }
        //查询blog有关的用户
        queryBlogUser(blog);
        //查询blog是否被点赞了
        isBlogLiked(blog);
        return Result.ok(blog);
    }

    private void isBlogLiked(Blog blog) {
        //获取登录用户，判断当前登录用户是否已经点赞
        UserDTO user = UserHolder.getUser();
        if (user == null) {
            //用户未登录，无需查询用户是否点赞
            return;
        }
        Long userId = UserHolder.getUser().getId();
        //如果未点赞，可以点赞，
        String key = BLOG_LIKED_KEY + blog.getId();
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        blog.setIsLike(score != null);
    }

    @Override
    public Result likeBlog(Long id) {
        //获取登录用户，判断当前登录用户是否已经点赞
        Long userId = UserHolder.getUser().getId();
        //如果未点赞，可以点赞，
        String key = BLOG_LIKED_KEY + id;
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        //数据库点赞数+1
        if (score == null) {
            //不存在代表没点过赞
            boolean isSuccess = update().setSql("liked = liked + 1").eq("id", id).update();
            if (isSuccess) {
                //保存用户到redis的set集合
                stringRedisTemplate.opsForZSet().add(key, userId.toString(), System.currentTimeMillis());
            }
        } else {
            //已经点过赞
            boolean isSuccess = update().setSql("liked = liked - 1").eq("id", id).update();
            if (isSuccess) {
                stringRedisTemplate.opsForZSet().remove(key, userId.toString());
            }
        }
        //如果已经点赞，数据库点赞数-1
        //把用户从redis的set集合里移除

        return Result.ok();
    }

    @Override //查询top5的点赞用户 zrange key 0 4
    public Result queryBlogLikes(Long id) {
        //查到的是userId和score，需要解析
        String key = BLOG_LIKED_KEY + id;
        Set<String> top5set = stringRedisTemplate.opsForZSet().range(key, 0, 4);
        if (top5set == null || top5set.isEmpty()) {
            return Result.ok(Collections.emptyList());
        }
        List<Long> ids = top5set.stream().map(Long::valueOf).collect(Collectors.toList());
        String idStr = StrUtil.join(",", ids);
//        List<UserDTO> userDTOList = userService.listByIds(ids)
// SELECT id,phone,password,nick_name,icon,create_time,update_time FROM tb_user WHERE id IN ( ? ) 数据库查询用in查询出来的顺序就变了，手动拼接sql
        List<UserDTO> userDTOList = userService.query()
                .in("id", ids)
                .last("ORDER BY FIELD(id," + idStr + ")").list()
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());

        return Result.ok(userDTOList);
    }

    @Override
    public Result saveBlog(Blog blog) {
        // 获取登录用户
        UserDTO user = UserHolder.getUser();
        blog.setUserId(user.getId());
        // 保存探店博文
        boolean isSave = save(blog);
        if (!isSave) {
            return Result.fail("新增笔记失败");
        }
        //查询笔记作者的所有粉丝，推送笔记id给所有粉丝 select * from tb_follow where follow_user_id =?
        List<Follow> follows = followService.lambdaQuery().eq(Follow::getFollowUserId, user.getId()).list();
        for (Follow follow : follows) {
            //获取所有的粉丝id
            Long userId = follow.getUserId();
            //推送到粉丝收件箱（sortedset key 就是粉丝id）
            String key = FEED_KEY + userId;
            stringRedisTemplate.opsForZSet().add(key, blog.getId().toString(), System.currentTimeMillis());
        }
        // 返回id
        return Result.ok(blog.getId());

    }

    @Override       //滚动式分页查询实现思路
    public Result queryBlogOfFollow(Long max, Integer offset) {
        //获得当前用户id
        Long userId = UserHolder.getUser().getId();
        //1.查询收件箱 ZREVRANGEBYSCORE key MAX MIN  WITHSCORES LIMIT OFFSET  count
        String key = FEED_KEY + userId;
        Set<ZSetOperations.TypedTuple<String>> tuples = stringRedisTemplate.opsForZSet()
                .reverseRangeByScoreWithScores(key, 0, max, offset, 2);
        if (tuples == null || tuples.isEmpty()) {
            return Result.ok();
        }
        //解析数据 blogId score（时间戳） offset
        ArrayList<Long> ids = new ArrayList<>(tuples.size());
        long minTime = 0;
        int os = 1;
        for (ZSetOperations.TypedTuple<String> tuple : tuples) { //5 4 4 2 2
            // 4.1.获取id
            ids.add(Long.valueOf(tuple.getValue()));
            // 4.2.获取分数(时间戳）
            long time = tuple.getScore().longValue();
            if (time == minTime) {
                os++;
            } else {
                minTime = time;
                os = 1;
            }

        }
        //从数据库查询blog数据封装返回
//        List<Blog> blogs = listByIds(ids);//是基于mysql的in来查的，不能保证有序性
        String idStr = StrUtil.join(",", ids);
        List<Blog> blogs = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Blog blog : blogs) {
            //查询blog有关的用户
            queryBlogUser(blog);
            //查询blog是否被点赞了
            isBlogLiked(blog);
        }

        ScrollResult r = new ScrollResult();
        r.setList(blogs);
        r.setOffset(os);
        r.setMinTime(minTime);
        return Result.ok(r);
    }

    private void queryBlogUser(Blog blog) {
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    }
}
